"So the geek in his high school who couldn't get a date was now buying, essentially, some of the most exotic women on planet Earth?"

"Any woman I wanted, yes."

"Were you also lavishing them with gifts?"

"Yes," Yagalla says.

He couldn't help himself. Yagalla bought many of his escorts expensive cars, furs, jewelry - even houses, costing him millions. But it was only when another woman introduced Mark to Sandy Bentley - who he began dating - that his spending really went into orbit.

"All the other girls were gold diggers, but Sandy was an educated gold digger," he says.

Asked how much he spent on her, Yagalla says, "About $6 to $7 million."

So how did he manage to pay for all of this?

"I was taking client money and there was no boundaries," he tells Van Sant.

"You were scamming your clients?"

"Yes."

Instead of investing their money in stocks, he used it to pay for his incredibly expensive sex-capades.

"I was running one big Ponzi scheme," Yagalla tells Van Sant.

"And in the end, people got hurt didn't they?"

"Very hurt."

FBI Special Agent Mike Degnan says Yagalla "just was the definition of greed... He just took whatever he could get and used it for his own personal use without any remorse for the people he was stealing it from."

But Mark Yagalla's world began to crumble.

"He owed a brokerage firm over $7 million and had bounced the check to them, and they were asking for their money," says Degnan.

"I dug such a deep hole - $40 or $50 million - that I could not get myself of," says Yagalla.

When Sandy Bentley got wind of it all, Yagalla says she dumped him. "...pretty much did not want to have anything to do with me. She was moving on."

Moving on, he says, but keeping most of his extravagant gifts including a fortune in jewels.

Police believe it was that jewelry that got Michael Tardio and Chris Monson murdered.

"Michael Tardio didn't have street smarts," says Cox. He and other investigators believe Sandy Bentley hatched a plan with Michael Tardio to sell some of Yagalla's gifts under the table to raise fast cash.

"Oh, I'm a sucker," Yagalla says. "Sandy Bentley was a total manipulator."